1. Field of the Invention
This invention relates, generally, to sanitization devices and wastewater treatment systems for either secondary treatment systems or stand-alone treatment systems.
2. Description of Prior Art
Mobile vessels such as motor vehicles, aircraft, and watercraft, especially those of larger size, are often equipped with a toilet. Of late there has been a greater emphasis on treatment of wastewater from these on-board toilets, known as heads. Some regulatory measures have been implemented which severely restrict the bodies of water into which watercraft can discharge untreated wastewater and other types of liquid discharge.
Other regulations allow discharge into certain bodies of water, but the effluent discharged must meet certain treatment standards.
The increased regulation and the desire of watercraft owners and operators to minimize the environmental impact of the discharge from their vessel have led to the development of various Marine Sanitation Devices (MSDs). Current Coast Guard regulations discuss three classes of MSDs. Type I MSDs treat wastewater with chemicals or by other means prior to discharging the treated wastewater from the vessel. Type I MSDs must meet certain standards for the discharge and the discharge can have limited visible floating solids. Type II MSDs operate similarly to Type I MSDs but must meet higher treatment standards. A Type III MSD is simply a holding tank.
The disadvantage of having only a holding tank (a Type III MSD) is that the vessel is severely restricted as to where it can discharge the untreated wastewater. Generally, the vessel will have to be on the high seas to discharge the untreated waste or will have the holding tank pumped out. Unauthorized discharges can result in serious penalties for the vessel operator.
Vessels up to and including those 65 feet or greater in length may use Type I, II, or III MSDs. Vessels 66 feet and over must have a Type II or Type III MSD. Because Type II MSDs are typically bigger and more expensive, and because they generally require more power than Type I MSDs, Type II MSDs are not commonly found on vessels 65 feet and smaller.
Type I devices include those which use the salinity of the water and electrical current to make hypochlorous acid (chlorine), which then treats the wastewater. These devices require salt water in order to operate. If used in fresh water, such as that found in many inland lakes and streams, the operator must add salt to the device. Other disadvantages of these devices are their bulk and the large amount of power necessary to operate them.
Another Type I MSD is a system in which the wastewater is flowed through a cartridge which contains a solid chlorine tablet. The tablet dissolves as the wastewater is treated. A further disadvantage of the electric current and chlorine cartridge systems discussed above is that they are limited to treating a single "flush" batch at a time. Neither of these Type I MSDs typically has any holding capacity.
Other Type I systems do have the capacity to hold more than one flush. However, the operator must carry and resupply the chemicals necessary for treatment of the wastewater in the tank.
Environmental concerns and stricter regulations are similarly generating increased awareness in land-based septic treatment systems. Many residences and businesses do not have access to municipal sewer treatment facilities and must treat wastewater on their own. Wastewater treatment systems, particularly those in rocky soil locations or those situated near rivers, lakes or other bodies of water, often incorporate a septic chamber along with a field-line or gravel bed for final waste contaminant removal prior to discharge into adjacent ditch or body of water. These conventional systems rely almost exclusively on anaerobic bacteria inside the septic tank and therefore require the aerobic bacterial activity of a field-line or gravel bed for final waste decontamination.
Traditional field-line or gravel bed wastewater treatment techniques do not sufficiently decontaminate the wastewater in certain geographical locations, either because of percolation in rocky soils or higher water tables near bodies of water.
Most improvements in the art has focused on incorporating aerobic bacteria in the septic system. This has been achieved by separating the septic tank into separate sections so that oxygen is only fed into the portion with aerobic bacteria. The continuous pumping of oxygen into the system requires large amounts of power to maintain the system.
For example, U.S. Pat. No. 5,531,894 to Ball, et al. describes a method of treating wastewater with a aerobic filter separate from the primary septic tank.
U.S. Pat. No. 5,549,818 to Hansel describes an apparatus for treating wastewater which uses an inverted cone clarifier configuration which divides a single tank into two distinct sections so that air may be delivered to the aerobic zone but not the anaerobic zone.
Additionally, the prior art devices typically require the periodic addition of chemicals such as chlorine to remove toxic fecal coliform bacteria from the final treated wastewater.
What is needed is a sanitation device which can both remedy the current problem of insufficient decontamination in the field-line or gravel bed by providing post-septic or post-mechanical treatment, and overcome the shortfalls of the devices which pump oxygen in order to increase levels of aerobic bacteria.